Reciprocating pump with full spring drive cycle



Jan. 31, 1967 A. R. STREETER 3,301,195

RECIPROCATING PUMP WITH FULL SPRING DRIVE CYCLE Filed June l, 1964 llwem/ United States Patent Oce 3,301,195 RECIPROCATING PUMP WITH FULL SPRINGv DRIVE CYCLE Allen R. Streeter, Flint, Mich., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed June 1, 1964. Ser. No. 371,381 4 Claims. (Cl. 103-150) This invention pertains to pumps and more particularly to reciprocating pumps including types suitable for providing fuel to automobile engines.

Reciprocating pumps'for automobiles are, as a general rule, positively driven by cam action through a plunger during suction strokes and are yieldingly driven by spring action during pressure strokes. Such a pump is disclosed in the United States Patent 2,868,135 granted January 13, 1959 in the name of D. R. 'Reinertson. This patented pump is a diaphragm pump but it will be seen as the description given below proceeds that the present invention is not limited in its application to such a pump but could beiapplied to a piston type pump.

An object of the present invention is to provide an improved reciprocating pump of simple construction, that is quiet in operation, capable of self-priming and also self-regulating its maximum pressure of discharge.

A feature of'the present invention is a reciprocating pump having a pumping member such as a diaphragm or piston and a reciprocablev plunger with a driving lostmotion connection between the member and plunger with two springs being employed, one determining the maximum discharge pressure and the other the degree of suction in a pumping chamber.

These and other important features of the application will now be described in detail in the specification and then pointed out more particularly in the appended claims.

in the drawings:

FIGUREl is a sectional view of an automotive diaphragm type fuel pump'as one embodiment of they present invention and an engine cam vshaft for actuating the pump and the parts beingshown as positioned at one extreme end of the pump stroke or at rest;

FIGURE 2 is similar to FIGURE 1 but showing the parts as positioned at the other extreme end of the pump stroke--i.e.-ready for self-priming; and

FIGURE 3 is similar to FIGURE l but showing the parts as positioned with pump discharge pressure requirements satisfied.

The pump shown in the drawings is much like that described in the Patent No. 2,868,135, referred to above, in that it includes a cover serving the same general purpose, that is, this cover serves to provide an inlet 12 with suitable one-way suction valve such as the valve 14 whereby liquid may be directed in one direction into a pumping chamber 16 dened between the cover 10 and a reciprocating pumping member 18 which is in the form of a exible diaphragm. A discharge passage and a oneway discharge valve in the cover 10 are not described herein as they are conventional.

The pump body includes not only a cover 10 but a supporting portion in the form of a cup 20 having an integral supporting flange 22. Interposed and clamped between the cover 10 and the body portion 20 is the periphery of a pumping diaphragm 18 which is securely held in fluid-tight relation by means of screws such as the screw 24. Within the cup portion 20 of the body is defined a spring chamber 26 and this is of sufficient capacity to accommodate a suction coil spring 28 surrounding an annular support 30 in which is enclosed a second pressure or heavy spring 32. The reciprocable portion of the diaphragm 18 is held between conventional protector plates 34 and 36. These plates and the diaphragm 18 are 3,301,195 lPatented Jan. 31, '1967 held together bymeans of a washer 38 and a shoulder 40 retained'on a stem 42. Also held with the diaphragm and the protector plates is one or the upper end 44 of the annular support 30; The annular support depends from the diaphragm 18 and bears an annular flange 46 at its bottom against which rests one end of the suction or light spring 28. The other end of the spring 28 acts against the pump body through a ring member fixed to the body. This ring has an opening 52 giving clearance for the annular support 30 as the latter must move with the diaphragm 18. The stem 42 is in telescopic relation with a plunger 60, The latter has a bore 62 to accommodate the stem42 and it also has a groove 64 whereby no fluid may be trapped between the lower end of thestem 42 and the bottom of the recess 62. The plunger i's'also enlarged as at 66 to retain or act against one end of the pressure spring 32. The other end of this spring acts against the bottom 44 of the support 30 thereby urging the diaphragm 18 upwardly. The pump body support is bored as at slidably to receive the plunger 60 so that the lower end of the latter is in engagement with a cam 72 forming a part of an internal combustion engine being served by the pump. It will be appreciated that forces to drive the pump are illustrated as being transmitted through the cam 72 but these forces may be transmitted by means of an accentric reciprocating pin or by other convenient means. The driving forces thus applied to the plunger 60 are transmitted through the pressure spring 32 to the diaphragm 18. The reciprocable movements of the diaphragm 18 induce alternate suction and pressure impulses in the pumping chamber 16. When the diaphragm moves downwardly, fuel is drawn into the pumping chamber 16 through the inlet valve 14 and when the diaphragm 13 moves upwardly the fluid is forced out from the chamber 16 through the outlet lcheck valve, not shown inthe drawings. Both valves are conventional in that they limit the fluid flow to only one direction.

In FIGURE 1, the pump parts are shown-'in rest positions, that is, as assumed at the bottom of the stroke.

There is a light load on the pressure spring 32 in this position, the spring being compressed sufficiently to in sure that it will not reach free length due to a build-up of manufacturing tolerances and a suliicient load to maintain constant contact of the plunger 60 against the cam 72.

One requirement of an automobile fuel pump is that it be self-priming. The priming position of the instant pump is illustrated in FIGURE 2. The carne 72 causes the plunger 60 to be pushed into the pump a predetermined distance. Forces are applied by the plunger to the pressure spring 32 and because this spring has a very high rate of dellection, it compresses very little when there are no resisting pressures applied downwardly on the diaphragm 18 as is the case during priming. The diaphragm 18 is, therefore, pushed into the pumping chamber 16 to the maximum extent. One end of the suction spring 28 also acts on the diaphragm 18 through the annular support 30 but the other end of the suction spring 28 acts against the pump body through the ring 50. Movement of the diaphragm 18 causes suction spring 28 to be compressed. The latter being a lighter spring than the spring 32 and having a much lower rate of deflection compresses more rapidly than the spring 32. The load on the spring 28 in this position is equal to the sum of the initial load on the pressure spring 32 plus the vacuum requirements to satisfy the installation multiplied by the effective area of the diaphragm 18.

As reciprocating motion of the plunger- 60 continues, the expansion of the springs 28 and 32 returns the diaphragm 18 to its position as illustrated in FIGURE 3 which is at it was in FIGURE 1. The plunger 60 and 3 the spring 32 have not as yet reached their original positions as FIGURE 3 represents a situation where the pumping requirements have been satislied. When these limits are approached the pressure of the uid in the chamber 16 acts against the diaphragm 18 and this force added to the working load on the suction spring 28 balances the load onthe pressure spring 32 and causes the diaphragm 18 to remain static in its down position which is the same as the bottom of a full stroke. Under these conditions, the continued reciprocating motion of the plunger 60 results in repeated expansion and compression of ,the spring 32 with no motion of the diaphragm until pumping is again required and pressure in chamber 16 is reduced upon which the diaphragm 18 will move and effectively operate.

The springs 28 and 32 are well guided and coaxially located at both ends so there is no tendency to buckle or for the scraping of some components against others. The lack of metal to metal impact results in quiet operation without necessitating critical tolerances. The recess 62 is of sufficient depth to eliminate any contact or impact between the stem 42 and the plunger 60 giving the stem 42 .and the annular support 30 a floating action at all times, i.e. a clearance exists at all times between the facing surfaces at the base of the stem 42.

Froml the above, it may be seen that during the suction or priming stroke of the pump through a proper balance of spring loads and working heights, the suction spring 28 overcomes the pressure spring 32 during the intake stroke. Conversely, until the engine fuel requirements are satised, the pressure spring 32 overcomes the suction spring 28 during the discharge stroke. With no metal to metal impact in the quiet driving mechanism, pump delivery is less prone to be characterized by surges and the fully activated lost-motion spring drive is more sensitive to engine requirements than is the case with conventional arrangements.

I claim:

1. A pump having a body and a reciprocable member cooperating to define a pumping chamber,i valve means for directing-fluid in one direction through said pumping chamber, a pump body support having a bore, a plunger mounted to extend through said bore and into said body and to reciprocate in said bore and on the same axis as said member, an actuator operatively connected to said plunger, a lost motion, connection between said plunger and said member, an annular support rigidly fixed to said member and disposed between the actuator and said member, a coil suct-ion spring and a coil pressure spring mounted coaxial with and on opposite sides of said annular support, said coil suction spring being compressed between said body and said annular support, andmsaid coil pressure spring being compressed between said a'n nular support and said plunger and being the sole driving connection therebetween, said suction spring" and said pressure spring being-arranged yso asV to react on said annular support in opposite directions `whereby said member and said annular support constitute a unit having a floating action at all times.

2. A pump as set forth in claim 1 in which 4said reciprocable member is a flexible pumping diaphragm, said pump body having a cup portion enclosing said springs and said annular support, and said? lost motion connection including a clearance at all times along said axis be# tween facing surfaces thereof. f

3. A pump as set forth in claim 1 inwhich said reciprocable member is movable only in alinear path with relation to said body, said lost motion connection having facing surfaces in said path, and a clearance existing at all times between said facing surfaces.

4. A pump as setforth in`claim 3 wherein said plunger has a bore for telescopically receiving a stem affixed to said member so as to constitute said lostrnotion connection between said plunger and said member.

References Cited by the Examiner DONLEY J. STOCKING, Primary Examiner.

WARREN E. COLEMAN, MARK NEWMAN,

W. L. FREEH, Assistant Examiner.y

E xamners. 

1. A PUMP HAVING A BODY AND A RECIPROCABLE MEMBER COOPERATING TO DEFINE A PUMPING CHAMBER, VALVE MEANS FOR DIRECTING FLUID IN ONE DIRECTION THROUGH SAID PUMPING CHAMBER, A PUMP BODY SUPPORT HAVING A BORE, A PLUNGER MOUNTED TO EXTEND THROUGH SAID BORE AND INTO SAID BODY AND TO RECIPROCATE IN SAID BORE AND ON THE SAME AXIS AS SAID MEMBER, AN ACTUATOR OPERATIVELY CONNECTED TO SAID PLUNGER, A LOST MOTION CONNECTION BETWEEN SAID PLUNGER AND SAID MEMBER, AN ANNULAR SUPPORT RIGIDLY FIXED TO SAID MEMBER AND DISPOSED BETWEEN THE ACTUATOR AND SAID MEMBER, A COIL SUCTION SPRING AN COIL PRESSURE SPRING MOUNTED COAXIAL WITH AND ON OPPOSITE SIDES OF SAID ANNULAR SUPPORT, SAID COIL SUCTION SPRING BEING COMPRESSED BETWEEN SAID BODY AND SAID ANNULAR SUPPORT, AND SAID COIL PRESSURE SPRING BEING COMPRESSED BETWEEN SAID ANNULAR SUPPORT AND SAID PLUNGER AND BEING THE SOLE DRIVING CONNECTION THEREBETWEEN, SAID SUCTION SPRING AND SAID PRESSURE SPRING BEING ARRANGED SO AS TO REACT ON SAID ANNULAR SUPPORT IN OPPOSITE DIRECTIONS WHEREBY SAID MEMBER AND SAID ANNULAR SUPPORT CONSTITUTE A UNIT HAVING A FLOATING ACTION AT ALL TIMES. 